The invention relates to a new and improved combined “framed-frameless” copper-releasing intrauterine contraceptive device (IUD), more particularly to a copper-releasing hybrid IUD with adaptable retention arm connected to frameless body for interval and postpartum contraception, reversible office sterilization and infection prevention.
The known frameless copper intrauterine device, called GyneFix® (EP 0191747) has six copper tubes, each 5 mm long and 2.2 mm wide, threaded on a length of suture material. The proximal end of the device is provided with an anchoring means (knot) for its fixation to the uterine wall in order to prevent that the device is pushed out by the uterus.
Another known device or system is the framed hormone-releasing Femilis® which is T-shaped and of which the retention arm is connected to a longitudinal branch constituting the stem of the T. Similarly an Ω-shaped retention arm has been described which is connected to a similar branch as the T-shaped Femilis hormone-releasing system (IUS, Intra Uterine System), constituting the stem of the device.
The object of the present invention is an intrauterine device of the T-shaped or Ω-shaped type of which the retention arm is connected to a frameless stem consisting only of the active contraceptive substance copper in the form of hollow tubes. This conception is completely different from conventional T-shaped copper IUDs or hormone-releasing IUSs. The majority of these devices are made of a plastic frame overlaid with copper, either copper tubes on the retention arm or a copper wire wound on the stem of the IUD. The present invention is different and serves an important purpose, as will be explained below.
It is indeed very important that women tolerate an IUD to avoid discontinuation of the method. Contraceptives are effective at preventing unintended pregnancy only if women or couples continue to use the method. Many women, particularly the young stop using hormonal methods such as the pill because of side effects. This results often in unplanned pregnancy and induced abortion. For this reason more and more public authorities in developed and developing countries promote and advocate the use of long-acting methods of contraception because they are not dependent on daily motivation and correct and consistent use. IUDs are probably the best methods to help reduce the soaring number of unintended pregnancies because they are long-acting and can easily be inserted and removed. However, most conventional IUDs are too big for many women, particularly the young because the uterine cavity of these women is significant smaller especially when they are less than 25 years of age or even adolescent. Dimensional compatibility of the intrauterine device (IUD) or intrauterine system (IUS) with the uterine cavity leads to high acceptability and continuation of use, a condition to continued use of the method and reduced risk of an unintended pregnancy. Incompatibility, on the other hand, leads to the opposite effect: cramping pain, abnormal or sometimes heavy menstrual bleeding, dislocation/expulsion and pregnancy.
The average width of the uterine cavity at the fundal level in nulliparous women between 15 and 34 years of age is approximately 24 mm (range 20-28 mm). The mean values and standard deviations of the fundal transverse diameter in women with parity one, two or three are only marginally greater. Other studies have found that the uterine volume increases with the presence of menarche, age and parity. Nulliparous and primiparous adolescents younger than 18 years old have a smaller uterine volume than nulliparous and primiparous women 20 to 40 years old.
Most conventional T-shaped IUDs have been invented for use by women with children of which the design and size of the IUD was based on casts made of extirpated uteri. An extirpated uterus has no tonus, contrarily to the uterus in vivo, and, therefore, the casts were too big and not reflective of the true size of a women's uterus. Moreover, the casts were made from extirpated uteri from parous women only. These measurements served as the bases for the development of the conventional T-shaped IUD of which most of them have a span of 32 mm. This span is too big to be comfortable accommodated in the majority of the uterine cavities of most women. Clinical studies conducted with smaller T-shaped devices have shown much better results as far as the occurrence of side effects is concerned. However, as smaller conventional copper IUD have less effective copper surface area, the improvement in comfort and tolerability seen with a reduction of size is sometimes achieved at the expense of the contraceptive effectiveness of the copper-releasing IUD.
The efficacy of a copper IUD depends on the release of copper ions into the uterine cavity and Fallopian tubes. Small amounts of copper have a strong antifertility effect as copper ions are toxic to sperm cells. They inactivate sperm. The greater the amount of copper, the better the protection against pregnancy. High load intrauterine copper devices are more effective than low load copper devices. Furthermore, the effective copper surface area which governs the amount of ions released must also be taken into account. With traditional copper IUDs which utilize copper wire wrapped around a plastic support, the part of the copper lying against the plastic is not exposed to the uterine environment and thus not available as a source of copper ions. Only the exposed surface of the wire is available for copper release and this should be taken into account. It has been calculated that 40% of the copper present on the traditional copper IUDs is not clinically available. The standard prior art “frameless” IUD (GyneFix®) (U.S. Pat. No. 4,708,134 or EP 0191747 incorporated herein by reference) with effective copper surface area of up to 330 mm2 is different than conventional copper wire wrapped IUDs such as the TCu380A IUD (Paragard®). GyneFix is composed of several small copper cylinders threaded on a flexible polymer suture string. The loose copper tubes are open from all sides and all surface areas are in contact with the endometrial environment. Thus, ion release occurs from both the exterior of the tube and also from its interior. As compared to a standard wire wrapped IUD of similar milligram load of copper, the effective surface area for GyneFix is substantially greater. This enhanced surface area and greater availability of copper ions allow for equivalent release rates even when a much smaller device is used. These differences in effective surface area between GyneFix and other copper IUDs explains the high effectiveness of the small frameless copper IUD.
Frameless devices are remarkably well tolerated by any uterus due to the absence of a frame, which eliminates spatial incompatibility with the uterine cavity. Because of its flexibility, embedment of the stem or transverse arm in the uterine wall does not occur, in contrast with conventional IUDs, particularly if the IUD is too big and the stem too long.
The purpose of the present invention therefore is to provide a T- or Ω-shaped copper-releasing IUD of reduced size, remarkably well tolerated, which can easily and safely be inserted, and which has a higher effective copper surface area than conventional and small-size copper IUDs to enhance the contraceptive effectiveness. In addition, by increasing the size of the copper tubes slightly, the lifespan of the IUD will be increased substantially. Long duration of action is important for IUD users as it is economical and may reduce certain health risks (e.g., infection) related to frequent replacement.
This purpose is reached by providing a T- or Ω-shaped IUD, including a longitudinal frameless branch constituting the body or stem of the device; the superior part or transverse arm, constituting the retaining member of the IUD, being linked to the upper part of the frameless body.
Referring to EP673 629 B1 (Van Os), the current application goes much further than the mere description of an IUD with flexible stem and transverse arm.
The current application is a combination of advantageous design elements to which important aspects related to the function as a contraceptive device, are added. These are described below as primary and secondary aims, as well as the further special characteristics of the invention.